ALUM-CARMINE. 99 



Zool. Stat. zu Neapel, 10, 3, 1892, p. 490). Carminic acid, 

 1 grm. ; chloride of aluminium, 3 grms. ; water, 200 c.c. Add 

 an antiseptic, as for carmalum. 



Use as carmalum. The stain is of a blue-violet colour, 

 very powerful, and elective. But it is not so pure a stain as 

 that of carmalum, plasma being more strongly coloured. It 

 is recommended only as a substitute for carmalum in cases 

 in which the latter is counter-indicated on account of the 

 presence of alum or the like. 



153. Alum- Carmine (GKENACHEE'S formula, Arch. mik. Anat., 

 xvi, 1879, p. 465). An aqueous solution (of 1 to 5 per cent, 

 strength, or any other strength that may be preferred) of com- 

 mon or ammonia alum is boiled for ten or twenty minutes 

 with i to 1 per cent, of powdered carmine. (It is perhaps 

 the safer plan to take the alum solution highly concentrated 

 in the first instance, and after boiling the carmine in it dilute 

 to the desired strength.) When cool filter. 



This stain must be avoided in the case of calcareous struc- 

 tures that it is wished to preserve (but see 155). 



TIZZONI (Bull. Sc. Med. Bologna, 1884, p. 259) arid PISENTI (Gazz. degli 

 Ospetali, No. 24 ; Zeit. f. wiss. Mik., ii, 1885, p. 378) add a small percent- 

 age of sulphate of sodium, with the object of enhancing the energy of the 

 stain. It should not be forgotten that sodium sulphate is a substance that 

 exercises a very peculiar action on nuclei (see PFITZNEE, Morph. Jahrb., xi, 

 1, 1885). 



GBIEB (Mem. Soc. Hal. Sci., t. vi, No. 9, 1887 ; Zeit. f. wiss. Mik., vii, 

 1, 1890, p. 47) gives a modification of Grenadier's formula which does not 

 appear to me rational. 



It has already been sufficiently repeated that alum-carmine 

 is one of the best stains to be found outside the coal-tar 

 colours. It is particularly to be recommended to the beginner, 

 as it is easy to work with ; it is hardly possible to overstain 

 with it (except muscle). Its chief defect is that it is not 

 very penetrating, and therefore quite unsuitable for staining 

 objects of considerable size in the mass. This defect may, 

 however, be overcome by employing the method of Zoltan 

 von Roboz (infra, 155), or by employing the acid formula 

 of Henneguy ( 156), if it be not convenient to use Mayer's 

 carmalum. 



The stain is permanent in balsam, and in aqueous media 

 if not acid. 



